1. Field of the Invention
This invention relates to an improved pedal mechanism for used in a sewing machine drive device.
2. Prior Art
FIGS. 7 to 9 shows a conventional device of this general type as disclosed in Japanese Laid-Open (Kokai) Utility Model Application No. 10188/86. A support plate 2 of a U-shaped cross-section horizontally extends between and supported by legs (not shown), and is spaced apart from the floor 1. A lever unit 30 outputs a variable-speed running instruction. A connecting wire 31 connects the lever unit 30 to a controller (not shown). Reference numeral 32 denotes a lever, and a unit casing 34 has a projection 35. The lever unit 30 is mounted on a mounting plate 36 which is fastened to the support plate 2 by bolts 38. Each support plate 42 is mounted on the mounting plate 36 by a hinge 44. A pedal mounting base 46 is fixedly connected to the support plate 42 by bolts 48. The pedal mounting base 46 has slots 49 extending generally vertically, and the bolts 48 extend through the slots 49, respectively, so that the height of the pedal base plate 46 above the floor 1 can be adjusted.
A speed pedal 51 and a switch pedal 52 both of which are of the foot-operated type are mounted on the pedal mounting base 46 by respective hinges 54. The two pedals 51 and 52 are disposed in juxtaposed relation and are slanting upwardly away from the hinge 54. A movable end of the speed pedal 51 is connected to the lever 32 through a connecting rod 56. Reference numeral 57 denotes a foot switch. The switch pedal 52 has a bent portion 58 at its distal end, and the bent portion 58 is disposed at a position corresponding to the projection 35 formed on the unit casing 34.
In order to enhance the productivity, the pedal mechanism of this type is operated by the operator who keeps standing during the operation. For this reason, the pedals are arranged in contact with the floor, and the sewing machine table is moved through casters to be set in a desired position in the sewing line as occasion calls, and then is used at such a position. Therefore, when the sewing is finished or interrupted, the pedal mechanism is required to be spaced apart from the floor and be kept in such a floating condition in order to enable the sewing machine table to be moved along the sewing line.
In the above conventional pedal mechanism, when the switch pedal 52 is raised, the pedal mounting base 46 and the support plate 42 are angularly moved about the hinge 44 in a counterclockwise direction as indicated by an arrow in FIG. 9, and the bent portion 58 is hooked to the projection 35. In this condition, the support plates 42 and the pedal mounting base 46, together with the two pedal 51 and 52, are kept spaced apart from the floor 1 as indicated by a dot-and-dash line in FIGS. 8 and 9. After such preparations are done, the sewing machine table can be moved to be set in a desired position in the sewing line.
After the sewing machine table is set in the sewing line, the bent portion 58 is disengaged from the projection 35, and the pedal mounting base 46 and the associated members are returned to their positions indicated by solid lines in FIGS. 8 and 9. In this case, when there exists a space between the underside of the pedal mounting base 46 and the floor, or when the pedal mounting base 46 is too high, which would be caused to the rugged surface of the floor or for other reasons, the bolts 4B are loosened to adjust the pedal mounting base 46 to eliminate such space and the inclination of the pedal mounting base 46 along the length of the support plate 2. After this adjustment, the speed of the sewing machine as well as the start and stop of the operation of the drive device can be controlled by foot-operating the speed pedal 51 and the switch pedal 52.
With the above construction of the conventional pedal mechanism for a sewing machine drive device, each time the sewing machine table is installed, it is usually necessary to loosen the bolts 48 to adjust the pedal mounting base 46 in accordance with the height of the support plate 2 relative to the floor 1, so that the pedal mounting base 46 can be held in contact with the floor 1. Further, the pedal mounting base 46 as well as the associated members is retained at only one point by the projection 35. Moreover, this retaining position is disposed out of the center, and therefore it is possible that the balance of the weight is adversely lost so that the pedal mounting base 46 may slide over the floor 1 when the sewing machine table is moved. Particularly when the bent portion 58 becomes disengaged from the projection 35 due to the shaking of the moving sewing machine table, the pedal mounting base 46 may drop to impinge on the floor 1, which may result in damage of the pedal mounting base.
With respect to a complicated operation of such a device, Japanese Utility Model Publication No. 1893/86 has proposed the following construction in an attempt to deal with such problem. In this construction, a foot switch plate is angularly moved through a hinge so as to lean against a support plate extending between legs. With this construction, the pedal plate can be easily moved upward and downward; however, there still remains the problem that such retaining is rather unstable, so that with a slight impact during the movement of the table, the pedal plate may accidentally drop or move downward.